Cone beam artifacts are a well known problem in circular computed tomography. The X-ray source cone angle in most advanced CT systems such as Toshiba AquilionONE is quite large, and CFK images suffer cone beam artifacts due to missing data in radon domain.
In one prior art approach, the artifact in circular cone beam CT is substantially removed by applying exact reconstruction based upon a theoretically complete trajectory such as a combination of a circular trajectory and a line trajectory. Although an additional line scan achieves a theoretically complete trajectory with a circular trajectory for exact reconstruction, the additional scan is often either unavailable or impractical to collect. Furthermore, since circular and line data are not simultaneously obtained, any change in motion or agent enhancement between the two scans causes data inconsistency between the two data sets and affect image accuracy. Lastly, the additional scan exposes a patient to additional radiation dose.
For the above reasons, it is of particular interest to accurately reconstruct image volume only from circular data. In another prior art approach, a scanogram is used to estimate a line data. Although this approach does not increase patient's radiation dose, cone beam artifacts are still observable even though the estimated line data helped reduce much of the artifacts. At the same time, any change in motion or agent enhancement is also causing some inaccuracy in the resulted images.
For the above described reasons, it is still desired to have a system and a method for substantially reducing artifacts in circular cone beam Computer Tomography (CT).